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The list of vitamins can be kind of confusing, what with all those B vitamins and a random K thrown in. But every name has its story.

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[SciShow intro]

In 1912, a Polish biochemist named Casimir Funk announced a discovery that would change medical science forever. He'd isolated a substance that was in brown rice but not white rice. It turned out to be the first known vitamin, or nutrient that humans need to stay healthy but, for the most part, can't manufacture inside our bodies.

More than a century later, our list of vitamins has expanded quite a bit. And, let's face it, their names make no sense whatsoever. Vitamin A, B, C, D, and E might seem logical at first, but don't get me started on the fact that there are eight different B vitamins that somehow number up to B12...? And what's Vitamin K doing all alone by itself in the middle of the alphabet?

Well it turns out that, like so many other things in science, the vitamins' names have a lot to do with history.  In this case, that history is chock-full of mistaken assumptions, and, as we've corrected those mistakes, we ended up with the alphanumeric soup that we call vitamins today. 

Now it all started with the invention of the word 'vitamin' itself. For a long time scientists had known that certain diet-related deficiencies caused diseases like pellagra, and scurvy, and rickets. They also knew that eating nothing but white rice led to a condition known as beriberi, which caused weakness and weight loss, and a whole host of other unpleasant symptoms. 

And yet those who ate brown rice, which still has its husk but has a shorter shelf-life, were totally fine. But nobody knew exactly what the difference was. Funk figured out that the husks in brown rice contained a chemical with an amine group. He thought he'd discovered a whole new class of amine-containing compounds that were vital to human life. And he was mostly right. 

Funk called these 'Vital amines' - 'Vitamines', and once scientists realized that they didn't all have to contain amine groups, they just shortened it to vitamins. Now it was super easy to spot the difference between the first two vitamins we isolated because one was fat-soluble, meaning that it was dissolved in lipids, while the other was water-soluble, and dissolved in water. 

The fat-soluble vitamin was discovered in milk and leafy greens by a team of researchers led by Elmer McCollum, who called it Vitamin A. And, somewhat questionably, he gave the name Vitamin B to the water-soluble amine that Funk had found in brown rice even though he found it first. Shoulda been A. 

Vitamin C was first proposed in 1919. By that point it was well-established that scurvy, a condition characterized by symptoms like anemia, swelling, and ulcers, was caused by a nutritional deficiency. Scientists figured there had to be a vitamin involved, even though they hadn't yet figured out what it was made of, so they just named it after the next letter in the alphabet, C.

So far, so good, all the vitamins going in alphabetical order. Scientists then learned that both vitamins A and B consisted of multiple variations and things started to go downhill. With the help of others' research, McCollum eventually figured out that vitamin A was actually made of two substances, and he was able to separate them. The one that prevented night-blindness kept the name Vitamin A, and he called the other part Vitamin D, since that was the next letter available. 

In the 1920s, scientists showed that fresh yeast, which contained what they'd been calling Vitamin B, protected against both pellagra and beriberi. But, after they heated it up, it didn't prevent pellagra anymore, so there had to be at least two separate vitamins in there, only one of which was surviving the heat. Some people started calling those vitamins F and G; others decided to name them B1 and B2, which became the more popular solution. At least until B2 also turned out to contain more than one vitamin. After that, things started getting messier. 

For example, for a while scientists thought they'd isolated a new vitamin and gave it the next name in the list, B4. But not only did B4 turn out to be made of 3 different compounds, adenine, carnitine, and choline, none of them are actually vitamins because humans don't need to get them from an outside source to stay healthy. That's why these days there is no vitamin B4, but there are ones with higher numbers because that's just how new water-soluble vitamins started getting named. 

Now, the next fat-soluble vitamin to be discovered was given the next available letter in the alphabet, so it is now known as vitamin E. But the Germans who discovered Vitamin K didn't follow that logic at all. The vitamin helps blood clot faster, and in German that's called 'koagulation' with a K, so they named the new substance Vitamin K.

And in case you're curious about the rest of the alphabet, the only letters that haven't had a proposed vitamin named after them at some point are O, W, X, Y, and Z. So the vitamins may look more like a randomly-generated password than a scientific list, but at least there are interesting reasons why.

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